The invention relates to a resistance module for increasing runup torque for a rotor of an electric machine comprising a rotor winding. The invention further relates to an exciter, a rotor and an electric machine, each having at least one such resistance module.
Such a resistance module is used for example in externally-excited synchronous machines with a rotor winding. During the runup phase such an electric machine has a comparatively large slip and runs up asynchronously. In such cases it is known that a reduction of the runup current in the rotor winding leads to an increase in the runup torque.
An electric motor with a rotor with two rotor windings is known from DE 39 59 52, wherein the rotor winding disposed radially further outwards has a large electrical resistance and the rotor winding disposed radially further inwards has a small electrical resistance. During the runup period the electric motor exhibits a high level of slip and the rotor winding with the large electrical resistance causes a high runup torque.